Driving mechanism



y L. A. McNABB 2,248,106

' DRIVING MECHANISM Filed Feb. 5, 1940 2 Sheets-Sheet 1IIIIIHII|llllIlllllllllllllllllllllllill g N E Luuls A. Ml: NAEIE J BJuly 8, 1941. MQNABB 2,248,106

' DRIVING MECHANISM v Filed Feb. '5, 1940 -2 She'etS- -Sheet 2 INVENTEIRLEILHEi Aql lc NAEE Wz My.

ATTY.

Patented July 8, 1941 TENT FiCE 2,248,106 DRIVING MECHANISM Louis A.McNabb,

ration of Illinois Wilmette, lill., assignor to The Bell & HowellCompany,

Chicago, Ill., a corpo- Application February 5, 1940, Serial No. 317,346

(c1. Fil -2.3)

9 Claims.

My invention relates particularly to the drive of sound record stripssuch as the photographic sound record film strips which are used in theproduction of sound accompanied motion pictures, although not limited tothis use alone.

The object of the invention resides in vision of novel and effectivedrive mechanism, involving a driven strip or belt engaging over arotatable drum or pulley which promotes accurately uniform constantmovement of the strip over the drum and corresponding accurately uniformrotation of the drum, to the instant end of promoting such accuratelyuniform constant drive of a feed perforated photographic sound recordfilm strip past a translating station operatively related with the stripat a'point where it passes over a sound drum for reducing or eliminatingsound distortion.

The invention will be better understood by reference to the accompanyingdrawings in i which-- V Figure 1 is a partial side elevation of a soundmotion picture projecting machine embodying my invention; v T

Figure 2 is a partial sectional view substantially on the line 2-2 ofFigure 1;

Figures 3 and 4 are perspective views of parts of the mechanism,hereinafter described; and

Figure 5 is a fragmentary side elevation of a modification of myinvention.

Referring to Figures 1 to 4 inclusive of the drawings, 1 designates theframe of a sound motion picture projecting machine, and disposedupwardly on the frame is a usual motion picture projecting mechanismincluding two vertically spaced rotating constant feed sprockets 2 whichengage usual feed perforations 3 ins. mo-

tion picture and sound record bearing photo-- graphic film strip 4 andfeed it to and from a prejection apertured intermittent feed guide 5wherein the film is fed intermittently in a downward direction by ausual intermittent feed mechanism not shown, the film being retained inengagement with the sprockets 2 by usual releasable retaining memb'ers5. See Figures 1 and 2.

A third rotating constant feed sprocket I is mounted on the frame 1below the lower sprocket 2 and engages the feed perforations of the filmstrip 4 for further constantly feeding the same, the film being retainedin engagement with the sprocket l by a usual releasable retaining member8. The sprockets 2 and l are driven in unison to feed the film at thesame rate by a usual driving mechanism not shown.

and driving the same,

the pro- A "sound drum 9 is rotatably mounted in a usual manner on theframe I on an axis in parallelism with those of the sprockets 2 and l, aflywheel It being connected with the drum to augment the momentumthereof as is usual.

The lower sprocket 2 and the sprocket 1 in their feed engagement of thestrip serve for constantly feeding the film strip Q in a loop i2 aboutand rotating the drum 9, see Figure 1, these sprockets engaging the filmstrip at both ends of theloop.

A stationary stud i3 is secured on the frame 4 above the loop 12, and amounting arm M is provided at its upper end with spaced bored portionsit which are engaged on the stud for the pivotal mounting of this armthereon. See Figures 1, 2 and 3. A bored sleeve 16 is secured on thestud 13 between the bored portions 15 of the arm it by means of a setscrew ii, and a torsion spring 18 encircles this sleeve and the stud l3and has one end thereof engaged with the sleeve, as designated at 19,and has the other end thereof engaged with the arm 14, as designated at2|, to yieldably urge the arm 14 in a direction clockwise in Figure 1.

The lower or free end of the arm 14 is provided with a stud 22 arrangedin parallelism with the pivotal axis of the necting member 23 is'provided with an extended intermediate bore 26 in which the stud 22 isengaged for the pivotal mounting of the arm 23 on the arm 14, a headedscrew 25 being screwthreaded into the projecting end of the stud toretain the arm 23 thereon. See particularly Figure '2.

I e arm 23 is provided with spaced parallel studs 26 between which thepivotal mounting of this arm, involving the bore 24, is disposed, andbored and flanged rollers 21 are rotatably mounted on these studs byplain bearings 28.

The rollers 21 engage the strip between the lower sprocket 2 and thesprocket 1 and the drum 9 in vertically spaced relation and in aclockwise direction in Figure 1 and are tensioned thereagainst and formbights 29 therein by reason of the pivotal axes of the mounting arm itand of the connecting arm 23 being disposed in a common vertical planeextending correspondingly' with that of the rollers 21 when tensionedagainst said stretches of the strip to provide bodily movement of theconnecting arm 23 in a path extending through the common plane of therollers 21 and by reason of the spring i8 yieldably urging the mountingarm M and the arm, and another arm-or contwo stretches of theintermediate the rollers21, clockwise or in the.

direction of said path opposed by engagement of the rollers 21 with thetwo stretches of the strip;

provided between the two-stretches of the film j strip 34 between thesprockets 33 and the drum 36 and comprises as follows: Another connect-ving arm 46 is provided with spaced rollers 41 ro- Accordingly,variations in tension of the 6 tatably mounted thereon as designated at48, and stretches of the film strip between the drum 9 is pivotallymounted intermediately of the rollers and the lower sprocket 2 andthesprocket I, are 41, as designated at 49. The rollers 61 formtransmitted, through the connecting arm 23 bights in the'aforesaidstretches of the film which may oscillate without interference from thestrip opposite the bights 44 formed by the rollers tensioning springl3,-from one to the other of 10 43and between these bights44 and thedrum 33. these stretches to the end of maintaining tension 1 The spring4| of the arm 38 serves to tension balance between these stretches andminimizing both pairs of rollers 43 and 41 against the interference withuniform rotation of the drum stretches of the film strip 34 between theand movement of the portion of the film strip sprockets 33 and the drum33,'and both of the engaged thereon, the momentum of the-drum l5connecting arms 42 and 46 function in cooperaand/or its flywheel orequivalent tending to maintion in a manner similar to the functioning ofthe tain the rate of rotation of the drum. connecting arm 23 nd itsrollers of Figures 1 As-shown, the internal bending friction of the and2, one or the ot er of the structures'of Figaforesaid stretches 'of thefilm strip as .well as the ures 1 and 2 and that of Figure 5 beinginvention. friction involved with the tensioning device, such While Ihave thus described my invention, I as the friction of the plainbearings 23 of the do not wish to be limited tothe precisedetailsderollers 21, serve in absorbing omillatory energy scribed as changesmay be readily made wi h so that such oscillatory energy does notaccumudeparung from the spirit of my invention, but

4 late by way of periodicity to amagnitude which having thus describedmy invention I claim as would disturb uniform rotation of the drum 9 and25 new and desire to secure by Letters Patent the the portionof the filmstrip engaged thereon. following:

To the end of augmenting the internal bend- 1. In a device of thecharacter described. the ing friction of .the film strip the rollers 21'are combination with a rotatable drum, of constant preferably relativelysmall in diameter to make feed means for feeding a strip over androtating the ,bights 23 relatively sharp. said-drum and operative onthestrlp on both Thus, both transient disturbances, sucha ma sides ofsaid drum, and means operative to transbe caused by casual irregularityof feed of the mit tension from one to the other of the-two film strip,the passage of a spliceoi, the film strip, stretches of the stripbetween said feed means or unit length variation of the film strip, andand i d um ompris n rc nn ns m mb rperiodic disturbances, su h-as may becaus'ed by her having tensioned operative relation at spaced Ieccentricity of the. feed? sprockets and points thereon with said stripon opposite sides of gears thereof or other manufacturing inacid m. amounting carrying said connecting ,curacies. are absorbed withoutunduly'increasing member for pivotal movement on 'anaxis interthe amountof energy transmitted by the film m dia e said spaced points and in turnmovablystrip or. unduly increasing the elastanee of th 40' mounted forbodily movement of said connecting 1 aforesaid stretches of thefilml'strip, I

Thecircumference of the rollers 31 are prefer ably longitudinallyconcave as shown at 33 in'Figure 2, the rollers." thus engaging the filmstrip- 1 only at the extreme edge portions thereof so that the recordportion of the film strip is not engaged with these rollers to preventdamage thereto, and

mon plane of said spaced related with said strip, and means operative onopposed by said tensioned 'opmember in a-path extending through the comvpoints when operatively and yieldably urging said mounting in thedlrec-- so that the feed perforated portion of the film strip is notengaged with these rollers to prevent I disturbance of the film stripthereby.

A usual optical slit translating device or "sound pick up," generallydesignatedat 3!. has opera- 1 tive relation with the film strip whileengaged on the drum. as is usual.

Referring to Figure v5 oi' the drawings, two verenga ing the usual feedperforations of a-film w'strip 34, serve to'constantly feed this filmstrip 3 in a loop '34 about and to rotates rotatable drum betweenvthesprockets 33 and the drum 38, and, 1 being identical'with that ofFigures 1 to 4 inclusive, comprises an arm 33 pivoted at andyieldablyurged clockwise by a spring 4|, a contically spaced rotatableconstant feed sprockets 33 are-driven in unison in a usual manner and,'

necting-arm 42 provided with spaced rollers 43 Zi'orming bizhts 44 inthe said two stretches of l ,the film strip 34, and plvotally mountedinterimediately of the rollers 43 on the free end of the iarnr33, asdesi nated at 43. this tension transmitting device functioning similarlyto that of Figures 1 to 4 inclusive" Another tension transmittingconnection is combination with a rotatable drum, of constant feed meansfor feeding a strip over and rotating said drum and operative on thestrip on both Q sides of said drum, and means operative to transmittension from one to the other 01' the two eng ing elements, amountingcarrying said connecting member for pivotal movement on an axisintermediate said spaced points and in turn movably mounted for bodilymovement of said connecting member in a path extending through thecommon plane of said spaced'points when said strip-engaging elements areengaged with said strip, and'meansoperative on and yieldably urging saidmounting in the direction of saidpath opposed by engagement of saidstrip engaging elements with said strip.

3. Ina-device of the character combination with a rotatable drum. ofconstant feed sprocket means for a feed perforated strip over androtating said drum and operative on the strip on both sides of saiddrum, and means operative to transmit ension from .one to the other ofthe two stretches of the strip between described, the

- pivotal axes of said feed means and said drum comprising a connectingmember providedwith spaced rollers tensioned against and forming bightsin said stretches, a pivoted arm on which said connecting member ispivotally mounted intermediate said rollers on an axis spaced from thepivotal axis of said arm, the pivotal axis of said arm and of saidconnecting member being disposed in a common plane extendingcorrespondingly with that of said rollers when engaged with said strip,

' and means operative on and yieldingly urging said arm in the directionof its pivotal movement opposed by engagement of said rollers with saidstretches.

4. In a device of the character described, the combination with arotatable drum, of constant feed sprocket means for feeding a feedperforated strip over and rotating said drum and operative on the stripon both sides of said drum, and means operative to transmit tension fromone to the other of the two stretches of the strip between said feedmeans and said drum comprising a connecting member provided with spacedrollers of relatively small diameter and having the circumferencesthereof longitudinally concave and tensioned against and forming bightsin said stretches, a mounting carrying said connecting member forpivotal movement on an axis intermediate said rollers and in turnmovably mounted for bodily movement of said connecting member in a pathextending through the common plane of said rollers when engaged withsaid strip, and means operative on and yieldably urging said mounting inthe direction of said path opposed by engagement of said rollers withsaid stretches,

5. In a device of the character described, the combination with arotatable drum. of constant feed sprocket means for feeding a feedperforated strip over and rotating'said drum and operative on the stripon both sides of said drum. and means operative to transmit tension fromone to the other of the two stretches of the strip between said feedmeans and said drum comprising a connecting member provided with spacedparallel studs and bored rollers of relatively small diameter and havingthe circumferences thereof longitudinally concave and rotatably mountedon said studs and tensioned against and forming bights 1 in saidstretches, a stationary stud, an arm pivotally mounted on saidstationary stud and on which said connecting member is pivotally mountedintermediate said rollers on an axis spaced from'the pi'votal axis ofsaid arm, the said arm and of said connecting member being disposed in acommon plane extending correspondingly with that of said rollers whenengaged with said strip, and a torsion spring surrounding saidstationary stud and operative on said arm to tension said rollersagainst said stretches of the strip.

6. In a device of the character described, the combination with arotatable drum, of constant feed means for feeding a strip over androtating said drum and operative on the strip on both sides of saiddrum, and means operative to transmit tension from one to the other ofthe two stretches of the strip between said feed means and said drumcomprising strip engaging elements tensioned against and forming bightsin said stretches, a connecting member operatively connected at spacedpoints thereon with said strip engaging elements, a mounting carryingsaid connecting member for pivotal movement on an axis intermediate saidspaced points and in turn movably mounted for bodily movement ofsaidconnecting member in a path extending through the common plane of saidspaced points when said strip engaging elements are engaged with saidstrip, means operative on and yieldably urging said mounting in thedirection of said path opposed by engagement of said strip engagingelements-with said stretches, additional strip engaging elementstensioned against and forming bights in said stretches opposite saidfirst mentioned bights, a second connecting member operatively connectedat spaced points thereon with I said additional strip engaging elements,and a r second mounting carrying said second connecting member forpivotal movement on an axis intermediate said spaced points thereof.

7. In a device of the character described, the combination with arotatable drum, of constant feed sprocket means for feeding a feedperforated strip over and rotating said drum and operative on thestripon both sides of said drum, and means operative to transmit tension fromone to the other of the two stretches of the strip between said feedmeans and said drum comprising a connecting member provided with spacedrollers tensioned against and forming bights in said stretches, a secondconnecting member provided with spaced rollers tensioned against andforming bights in said stretches opposite said first mentioned bights, amounting carrying said first mentioned connecting member for pivotalmovement on an axis intermediate said first mentioned rollers and inturn movably mounted for bodily movement of .said first mentionedconnecting member in a path extending through thecommon plane of saidfirst mentioned rollers when engaged with said strip, a second mountingcarrying said second connecting member for pivotal movement intermediatesaid second mentioned rollers, and resilient means operative on andyieldably urging said first mentioned mounting in the direction of saidpathropposed by engagement ,of said first mentioned rollers with saidstretches.

8. In a device of the character described, the 1 combination with arotatable drum and a flywheel connected therewith, of constant feedsprocket means for feeding a feed perforated optical record strip overand rotating said drum and engaging the strip on 'both sides of saiddrum, an optical translating device having operative relation with Iopposite sides of said drum, a mounting carrying said connecting memberfor pivotal movement on an axis intermediate said spaced points and inturn mounted for bodily movement of said connecting member in a pathextending through the common plane of said spaced points whenoperatively related with said strip, and means operative on andyieldably urging said mounting in the direction of said path opposed bysaid tensioned operative relation.

9. In a device of the character described, the combination with arotatable drum and a flywheel connected therewith, of constant feedsprocket means for feeding a feed perforated optical record strip overand rotating said drum and engaging the strip on both sides of saiddrum, an optical translating device having operative relation with saidstrip while engaged on said drum, and means operative to transmittension from one to the other of the two stretches of the strip betweensaid feed means and said drum comprising a conin a path extendingthrough the common plane necting member provided with spaced rollers ofsaid rollers when engaged with said strip, and tensioned against andforming bights in said ymeans operative-on and yieldably urging saidstretches, amounting carrying said connecting mounting in the directionof said path opposed by member for pivotal movement on an axis intere 5eengagement of said rollers with said'stretches.

mediate said rollers and in turn movably mounted 1 for bodily movementof said connecting member LOUIS A. McNAB B.

